Magnavox input issue! Very annoying!

I got an old Magnavox from a friend, and i'm trying to get the input to work. It didn't have a remote so a bought a universal remote, but all it does when you press Input is press 0. I can't access any input channels at all. The tv doesn't have a menu button on it so that's no-go either. Just power, channel, volume, display, status. Any suggestions?